This invention relates to material dispensers and, more particularly, to a dry food material dispenser, such as a sugar dispenser.
In the prior art, dispensing food matter, such as sugar, to the public in a sanitary way in individual portions, has been fraught with problems. Open containers are generally considered to be unsanitary. Ofter, sugar is packaged in individual paper containers for this very reason. While small quantities of sugar can be placed in individual hand-held containers, I know of no commercially available dispenser which can retain a large quantity of sugar for dispensing individual portions. This is, no doubt, due to the fact that a large quantity of sugar which sits in a container overnight has a tendency to cake and this quantity, when mechanically vibrated, for example, by opening the dispenser, will closely and tightly pack.
Apparently, this caking occurs because the sugar deliquesces on exposure to moisture in the atmosphere and then hardens into an almost concrete-like mass. This exposure occurs initially at the openings into the container and thus, if a container sits overnight, it becomes difficult and sometimes impossible to dispense sugar through the opening. Again, it is to be emphasized that we are talking here about large capacity containers rather than small containers which can be inverted in order to pour the sugar from the container through a small opening. Such small capacity containers obviously have neither the packing problem nor the caking problem since the sugar does not lie against the opening when in storage. Of course, even a small container will tend to cake if the sugar is left for a considerable length of time. Generally speaking, such small containers do not have any means for breaking up the cake of sugar short of removing the cap and inserting a utensil into the mass of sugar.
I have attempted, unsuccessfully, to solve the problems of dispensing the sugar in individual portions by using a manually actuated plunger or piston. Such a system will not work due to frictional forces and packing. The packing is caused by vibrations of the mechanism settling the particulate matter against the piston causing such friction as to totally prevent movement; thus making a hand operated dispenser impossible.
Furthermore, a system utilizing a piston-actuated diaphragm such as that shown in the G. Plura U.S. Pat. No. 3,391,833 would be unsuitable in a manual sugar dispenser. For one thing, the short stroke enlarged faced diaphragm would require tremendous force. More importantly, such a device does not move through the particulate matter, but rather attempts to displace it. This would be totally impracticable when dealing with a material which forms a hard concrete-like cake, such as sugar.